Adjacent device isolation

ABSTRACT

An integrated circuit (IC) device may include a first active transistor of a first-type in a first-type region. The first active transistor may have a first-type work function material and a low channel dopant concentration in an active portion of the first active transistor. The IC device may also include a first isolation transistor of the first-type in the first-type region. The second active transistor may have a second-type work function material and the low channel dopant concentration in an active portion of the first isolation transistor. The first isolation transistor may be arranged adjacent to the first active transistor.

BACKGROUND

1. Field

Aspects of the present disclosure relate to semiconductor devices, andmore particularly to isolation between adjacent devices.

2. Background

As integrated circuit (IC) technology advances, device geometries arereduced. Reducing the geometry and “pitch” (spacing) between devices maycause devices to interfere with each other in terms of proper operation.

Fin-based devices are three-dimensional structures on the surface of asemiconductor substrate. A fin-based transistor, which may be afin-based metal-oxide-semiconductor field-effect transistor (MOSFET),may be referred to as a FinFET. A nanowire field-effect transistor (FET)is also a three-dimensional structure on the surface of a semiconductorsubstrate. A nanowire FET includes doped portions of the nanowire thatcontact a channel region and serve as the source and drain regions ofthe device. A nanowire FET is also an example of a MOSFET device.

The performance of MOSFET devices can be affected by numerous factorsincluding channel length, strain and external resistance. Onesubstantial factor that contributes to the performance of MOSFET devicesis interference between adjacent devices. Interference between adjacentdevices is a device performance and scaling limiter for advancedtechnology nodes in which the geometry and pitch between devices isdramatically reduced.

SUMMARY

An integrated circuit (IC) device may include a first active transistorof a first-type in a first-type region. The first active transistor mayhave a first-type work function material and a low channel dopantconcentration in an active portion of the first active transistor. TheIC device may also include a first isolation transistor of thefirst-type in the first-type region. The second active transistor mayhave a second-type work function material and the low channel dopantconcentration in an active portion of the first isolation transistor.The first isolation transistor may be arranged adjacent to the firstactive transistor.

A method for altering a work function material of an isolationtransistor within an integrated circuit (IC) device is described. Themethod may include exposing a first-type work function material of theisolation transistor disposed adjacent to a first-type active transistorin a first-type region. The method may also include etching thefirst-type work function material of the isolation transistor to form asecond-type work function material for the isolation transistor withinthe first-type region. The method may further include depositing aconductive fill material on the second-type work function material ofthe isolation transistor.

An integrated circuit (IC) device may include a first active transistorof a first-type in a first-type region. The first active transistor mayhave a first-type work function material and a low channel dopantconcentration in an active portion of the first active transistor. TheIC device may also include a first means for isolating the first activetransistor. The first isolating means may be arranged adjacent to thefirst active transistor.

This has outlined, rather broadly, the features and technical advantagesof the present disclosure in order that the detailed description thatfollows may be better understood. Additional features and advantages ofthe disclosure will be described below. It should be appreciated bythose skilled in the art that this disclosure may be readily utilized asa basis for modifying or designing other structures for carrying out thesame purposes of the present disclosure. It should also be realized bythose skilled in the art that such equivalent constructions do notdepart from the teachings of the disclosure as set forth in the appendedclaims. The novel features, which are believed to be characteristic ofthe disclosure, both as to its organization and method of operation,together with further objects and advantages, will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, referenceis now made to the following description taken in conjunction with theaccompanying drawings.

FIG. 1 illustrates a perspective view of a semiconductor wafer in anaspect of the present disclosure.

FIG. 2 illustrates a cross-sectional view of a die in accordance with anaspect of the present disclosure.

FIG. 3 illustrates a cross-sectional view of a metal-oxide-semiconductorfield-effect transistor (MOSFET) device in an aspect of the presentdisclosure.

FIG. 4 illustrates a fin field-effect transistor (FinFET) in accordancewith an aspect of the present disclosure.

FIG. 5 illustrates a perspective view of an integrated circuit (IC)device in which adjacent devices are isolated by altering a workfunction material of the isolation devices according to an aspect of thepresent disclosure.

FIGS. 6A-6J are cross-sectional views illustrating isolation of sub-finregions of the IC device of FIG. 5 in accordance with an aspect of thepresent disclosure.

FIGS. 7A-7I illustrate cross-sectional views showing alteration of awork function material of the isolation devices of the IC device of FIG.5 in an aspect of the present disclosure.

FIG. 8 illustrates a perspective view of an integrated circuit (IC)device in which adjacent devices are isolated by altering a workfunction material of the isolation devices according to an aspect of thepresent disclosure.

FIG. 9 illustrates a layout view of an IC device in which adjacentdevices are isolated by altering a work function material of isolationdevices according to an aspect of the present disclosure.

FIGS. 10A and 10B illustrate a method for fabricating an IC device inwhich adjacent devices are isolated by altering a work function materialof isolation devices in accordance with an aspect of the presentdisclosure.

FIG. 11 is a block diagram showing an exemplary wireless communicationsystem in which an aspect of the disclosure may be advantageouslyemployed.

FIG. 12 is a block diagram illustrating a design workstation used forcircuit, layout, and logic design of a fin-based structure according toone configuration.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. It will be apparent,however, to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts. As described herein, the use of the term“and/or” is intended to represent an “inclusive OR”, and the use of theterm “or” is intended to represent an “exclusive OR”.

Semiconductor fabrication processes are often divided into three parts:a front-end-of-line (FEOL), a middle-of-line (MOL) and aback-end-of-line (BEOL). Front-end-of-line processes include waferpreparation, isolation, well formation, gate patterning, spacers, anddopant implantation. A middle-of-line process includes gate and terminalcontact formation. The gate and terminal contact formation of themiddle-of-line process, however, is an increasingly challenging part ofthe fabrication flow, particularly for lithography patterning.Back-end-of-line processes include forming interconnects and dielectriclayers for coupling to the FEOL devices. Formation of the FEOL devicesmay involve isolation of adjacent devices to reduce neighboring deviceinterference.

As integrated circuit (IC) technology advances, device geometries arereduced. The geometry and “pitch” (spacing) between devices hassubstantially reduced in advanced logic technology. For example, in aseven (7) nanometer logic technology, the fin pitch is highly scaled(e.g., 21 to 24 nanometers) and the contacted gate pitch is alsoaggressively reduced (e.g., 39 to 45 nanometers).

Fin-based devices represent a significant advance in IC technology.Fin-based devices are three-dimensional structures on the surface of asemiconductor substrate. A fin-based transistor, which may be afin-based metal-oxide-semiconductor field-effect transistor (MOSFET),may be referred to as a FinFET. A nanowire field-effect transistor (FET)also represents a significant advance in IC technology. Agate-all-around (GAA) nanowire-based device is also a three-dimensionalstructure on the surface of a semiconductor substrate. A GAAnanowire-based device includes doped portions of the nanowire thatcontact a channel region and serve as the source and drain regions ofthe device. A GAA nanowire-based device is also an example of a MOSFETdevice.

The performance of MOSFET devices can be affected by numerous factorsincluding channel length, strain and external resistance. For example,semiconductor device operation often involves isolating one device fromanother. As a result, interference between adjacent devices is onesubstantial factor that may contribute to degraded performance of MOSFETdevices. In particular, interference between adjacent devices is adevice performance and scaling limiter for advanced technology nodes inwhich the geometry and spacing between devices is dramatically reduced.

In a planar structure, a fin-based structure, a GAA nanowire-basedstructure or other like three-dimensional structures, adjacent devices,such as transistors, may be physically and/or electrically isolated. Aphysical disconnect between adjacent active areas may be performed todisconnect the active areas of adjacent transistors. The disconnectionmay involve physically breaking the active areas using, for example, acutting step to disconnect the active areas of adjacent transistors orsome other physical barrier between two adjacent devices. While such anapproach may provide complete electrical isolation, the physicaldisconnection (e.g., the cutting step) is not self-aligned. Lack ofself-alignment in the physical disconnection may lead to performancevariability, while involving a device area penalty to account for thephysical barrier created between the two adjacent devices.

An electrical disconnect between adjacent active areas may be performedto electrically disconnect the active area of an adjacent isolationdevice. In this electrical isolation, a nearby (or adjacent) transistormay be used as an isolation device. Such an isolation device may bereferred to as a “tie-off” device in which the active area of thetie-off device is set to an off state. An off state may be differentdepending on the type of charge carrying device. For example, in ann-type device, the tie-off device may tie a gate to a low potential,whereas for a p-type device the tie-off device may tie the gate to ahigh potential. A gate of an isolation transistor (e.g., a tie-offdevice) may be biased to place the isolation transistor in an OFF stateand provide isolation for an adjacent active device.

In related art approaches, the tie-off device (e.g., the gate of atransistor) may be of the same charge carrier as the desired activedevice. In such cases, the tie-off device may be fabricated usingsimilar processing steps to those used to fabricate active devices. Thatis, the processing steps used to fabricate the gate, source and drain,as well as the gate contacts for the tie-off device, and thecharacteristics (e.g., threshold voltage (Vt), leakage current I_(off),gate length, etc.) of the tie-off device will be similar to those usedto fabricate the active device. For example, if the active device is ahigh performance device, a threshold voltage (Vt) of the active devicemay be low. As a result, the isolation device is also fabricated with alow threshold voltage. Without physical disconnection, a non-negligibleleakage current I_(off) will exist across the isolation device becauseof the low threshold voltage (e.g., the voltage low above which thedevice is activated).

Various aspects of the disclosure provide techniques for isolatingadjacent devices by altering a work function material of the isolationdevice. The process flow for altering a work function material of eitheran active device or an isolation device may include front-end-of-line(FEOL) processes, middle-of-line (MOL) processes, and back-end-of-line(BEOL) processes. It will be understood that the term “layer” includesfilm and is not to be construed as indicating a vertical or horizontalthickness unless otherwise stated. As described herein, the term“substrate” or may refer to a substrate of a diced wafer or may refer tothe substrate of a wafer that is not diced. Similarly, the terms waferand die may be used interchangeably unless such interchanging would taxcredulity.

Aspects of the present disclosure include an innovative integration flowto alter a work function material disposed on the active source/drainregions of either a fin-based active device or a fin-based isolationdevice. Additional aspects of the present disclosure can alter a workfunction material disposed on the active source/drain regions ofgate-all-around (GAA) nanowire-based devices and other likethree-dimensional structure to reduce leakage current within theisolation device. Adjacent device isolation using altered work functionmaterials may enable operation within the reduced device geometries ofadvanced logic technology, such as seven (7) nanometer logic technologyand beyond. A work function alteration is self-aligned to the activedevices and may be performed using existing materials and processcapabilities with no additional steps. This aspect of the presentdisclosure also provides a reduction in the fabrication penalty forforming an isolation device within the active circuit area.

One aspect of the present disclosure alters the work function materialof either the active device or the tie-off device, such that the activedevice and the corresponding tie-off device have different work functionmaterials. For high performance active devices, which have a lowthreshold voltage, having a similar work-function material (e.g., ap-type work function metal (PWFM) or an n-type work function metal(NWFM)) in the corresponding tie-off device increases the possibility ofleakage current. By altering the work function material of the eitheractive device or the tie-off device, which may be done in the gatestack, the threshold of the tie-off device is changed from a lowerthreshold voltage to a higher threshold voltage. This may change theleakage current and also may provide isolation between the active deviceand other active devices, such as adjacent active devices on anintegrated circuit.

FIG. 1 illustrates a perspective view of a semiconductor wafer in anaspect of the present disclosure. A wafer 100 may be a semiconductorwafer, or may be a substrate material with one or more layers ofsemiconductor material on a surface of the wafer 100. When the wafer 100is a semiconductor material, it may be grown from a seed crystal usingthe Czochralski process, where the seed crystal is dipped into a moltenbath of semiconductor material and slowly rotated and removed from thebath. The molten material then crystalizes onto the seed crystal in theorientation of the crystal.

The wafer 100 may be a compound material, such as gallium arsenide(GaAs) or gallium nitride (GaN), a ternary material such as indiumgallium arsenide (InGaAs), quaternary materials, or any material thatcan be a substrate material for other semiconductor materials. Althoughmany of the materials may be crystalline in nature, polycrystalline oramorphous materials may also be used for the wafer 100.

The wafer 100, or layers that are coupled to the wafer 100, may besupplied with materials that make the wafer 100 more conductive. Forexample, and not by way of limitation, a silicon wafer may havephosphorus or boron added to the wafer 100 to allow for electricalcharge to flow in the wafer 100. These additives are referred to asdopants, and provide extra charge carriers (either electrons or holes)within the wafer 100 or portions of the wafer 100. By selecting theareas where the extra charge carriers are provided, which type of chargecarriers are provided, and the amount (density) of additional chargecarriers in the wafer 100, different types of electronic devices may beformed in or on the wafer 100.

The wafer 100 has an orientation 102 that indicates the crystallineorientation of the wafer 100. The orientation 102 may be a flat edge ofthe wafer 100 as shown in FIG. 1, or may be a notch or other indicia toillustrate the crystalline orientation of the wafer 100. The orientation102 may indicate the Miller Indices for the planes of the crystallattice in the wafer 100.

The Miller Indices form a notation system of the crystallographic planesin crystal lattices. The lattice planes may be indicated by threeintegers h, k, and l, which are the Miller indices for a plane (hkl) inthe crystal. Each index denotes a plane orthogonal to a direction (h, k,l) in the basis of the reciprocal lattice vectors. The integers areusually written in lowest terms (e.g., their greatest common divisorshould be 1). Miller index 100 represents a plane orthogonal todirection h; index 010 represents a plane orthogonal to direction k, andindex 001 represents a plane orthogonal to f. For some crystals,negative numbers are used (written as a bar over the index number) andfor some crystals, such as gallium nitride, more than three numbers maybe employed to adequately describe the different crystallographicplanes.

Once the wafer 100 has been processed as desired, the wafer 100 isdivided up along dicing lines 104. The dicing lines 104 indicate wherethe wafer 100 is to be broken apart or separated into pieces. The dicinglines 104 may define the outline of the various integrated circuits thathave been fabricated on the wafer 100.

Once the dicing lines 104 are defined, the wafer 100 may be sawn orotherwise separated into pieces to form die 106. Each of the die 106 maybe an integrated circuit with many devices or may be a single electronicdevice. The physical size of the die 106, which may also be referred toas a chip or a semiconductor chip, depends at least in part on theability to separate the wafer 100 into certain sizes, as well as thenumber of individual devices that the die 106 is designed to contain.

Once the wafer 100 has been separated into one or more die 106, the die106 may be mounted into packaging to allow access to the devices and/orintegrated circuits fabricated on the die 106. Packaging may includesingle in-line packaging, dual in-line packaging, motherboard packaging,flip-chip packaging, indium dot/bump packaging, or other types ofdevices that provide access to the die 106. The die 106 may also bedirectly accessed through wire bonding, probes, or other connectionswithout mounting the die 106 into a separate package.

FIG. 2 illustrates a cross-sectional view of a die 106 in accordancewith an aspect of the present disclosure. In the die 106, there may be asubstrate 200, which may be a semiconductor material and/or may act as amechanical support for electronic devices. The substrate 200 may be adoped semiconductor substrate, which has either electrons (designatedN-channel) or holes (designated P-channel) charge carriers presentthroughout the substrate 200. Subsequent doping of the substrate 200with charge carrier ions/atoms may change the charge carryingcapabilities of the substrate 200.

Within a substrate 200 (e.g., a semiconductor substrate), there may bewells 202 and 204, which may be the source and/or drain of afield-effect transistor (FET), or wells 202 and/or 204 may be finstructures of a fin structured FET (FinFET). Wells 202 and/or 204 mayalso be other devices (e.g., a resistor, a capacitor, a diode, or otherelectronic devices) depending on the structure and other characteristicsof the wells 202 and/or 204 and the surrounding structure of thesubstrate 200.

The semiconductor substrate may also have a well 206 and a well 208. Thewell 208 may be completely within the well 206, and, in some cases, mayform a bipolar junction transistor (BJT). The well 206 may also be usedas an isolation well to isolate the well 208 from electric and/ormagnetic fields within the die 106.

Layers (e.g., 210 through 214) may be added to the die 106. The layer210 may be, for example, an oxide or insulating layer that may isolatethe wells (e.g., 202-208) from each other or from other devices on thedie 106. In such cases, the layer 210 may be silicon dioxide, a polymer,a dielectric, or another electrically insulating layer. The layer 210may also be an interconnection layer, in which case it may comprise aconductive material such as copper, tungsten, aluminum, an alloy, orother conductive or metallic materials.

The layer 212 may also be a dielectric or conductive layer, depending onthe desired device characteristics and/or the materials of the layers(e.g., 210 and 214). The layer 214 may be an encapsulating layer, whichmay protect the layers (e.g., 210 and 212), as well as the wells 202-208and the substrate 200, from external forces. For example, and not by wayof limitation, the layer 214 may be a layer that protects the die 106from mechanical damage, or the layer 214 may be a layer of material thatprotects the die 106 from electromagnetic or radiation damage.

Electronic devices designed on the die 106 may comprise many features orstructural components. For example, the die 106 may be exposed to anynumber of methods to impart dopants into the substrate 200, the wells202-208, and, if desired, the layers (e.g., 210-214). For example, andnot by way of limitation, the die 106 may be exposed to ionimplantation, deposition of dopant atoms that are driven into acrystalline lattice through a diffusion process, chemical vapordeposition, epitaxial growth, or other methods. Through selectivegrowth, material selection, and removal of portions of the layers (e.g.,210-214), and through selective removal, material selection, and dopantconcentration of the substrate 200 and the wells 202-208, many differentstructures and electronic devices may be formed within the scope of thepresent disclosure.

Further, the substrate 200, the wells 202-208, and the layers (e.g.,210-214) may be selectively removed or added through various processes.Chemical wet etching, chemical mechanical planarization (CMP), plasmaetching, photoresist masking, damascene processes, and other methods maycreate the structures and devices of the present disclosure.

FIG. 3 illustrates a cross-sectional view of a metal-oxide-semiconductorfield-effect transistor (MOSFET) device 300 in an aspect of the presentdisclosure. The MOSFET device 300 may have four input terminals. Thefour inputs are a source 302, a gate 304, a drain 306, and a substrate308. The source 302 and the drain 306 may be fabricated as the wells 202and 204 in the substrate 308, or may be fabricated as areas above thesubstrate 308, or as part of other layers on the die 106. Such otherstructures may be a fin or other structure that protrudes from a surfaceof the substrate 308. Further, the substrate 308 may be the substrate200 on the die 106, but substrate 308 may also be one or more of thelayers (e.g., 210-214) that are coupled to the substrate 200.

The MOSFET device 300 is a unipolar device, as electrical current isproduced by only one type of charge carrier (e.g., either electrons orholes) depending on the type of MOSFET. The MOSFET device 300 operatesby controlling the amount of charge carriers in the channel 310 betweenthe source 302 and the drain 306. A voltage Vsource 312 is applied tothe source 302, a voltage Vgate 314 is applied to the gate 304, and avoltage Vdrain 316 is applied to the drain 306. A separate voltageVsubstrate 318 may also be applied to the substrate 308, although thevoltage Vsubstrate 318 may be coupled to one of the voltage Vsource 312,the voltage Vgate 314 or the voltage Vdrain 316.

To control the charge carriers in the channel 310, the voltage Vgate 314creates an electric field in the channel 310 when the gate 304accumulates charges. The opposite charge to that accumulating on thegate 304 begins to accumulate in the channel 310. The gate insulator 320insulates the charges accumulating on the gate 304 from the source 302,the drain 306, and the channel 310. The gate 304 and the channel 310,with the gate insulator 320 in between, create a capacitor, and as thevoltage Vgate 314 increases, the charge carriers on the gate 304, actingas one plate of this capacitor, begin to accumulate. This accumulationof charges on the gate 304 attracts the opposite charge carriers intothe channel 310. Eventually, enough charge carriers are accumulated inthe channel 310 to provide an electrically conductive path between thesource 302 and the drain 306. This condition may be referred to asopening the channel of the FET.

By changing the voltage Vsource 312 and the voltage Vdrain 316, andtheir relationship to the voltage Vgate 314, the amount of voltageapplied to the gate 304 that opens the channel 310 may vary. Forexample, the voltage Vsource 312 is usually of a higher potential thanthat of the voltage Vdrain 316. Making the voltage differential betweenthe voltage Vsource 312 and the voltage Vdrain 316 larger will changethe amount of the voltage Vgate 314 used to open the channel 310.Further, a larger voltage differential will change the amount ofelectromotive force moving charge carriers through the channel 310,creating a larger current through the channel 310.

The gate insulator 320 material may be silicon oxide, or may be adielectric or other material with a different dielectric constant (k)than silicon oxide. Further, the gate insulator 320 may be a combinationof materials or different layers of materials. For example, the gateinsulator 320 may be Aluminum Oxide, Hafnium Oxide, Hafnium OxideNitride, Zirconium Oxide, or laminates and/or alloys of these materials.Other materials for the gate insulator 320 may be used without departingfrom the scope of the present disclosure.

By changing the material for the gate insulator 320, and the thicknessof the gate insulator 320 (e.g., the distance between the gate 304 andthe channel 310), the amount of charge on the gate 304 to open thechannel 310 may vary. A symbol 322 showing the terminals of the MOSFETdevice 300 is also illustrated. For N-channel MOSFETs (using electronsas charge carriers in the channel 310), an arrow is applied to thesubstrate 308 terminal in the symbol 322 pointing away from the gate 304terminal. For p-type MOSFETs (using holes as charge carriers in thechannel 310), an arrow is applied to the substrate 308 terminal in thesymbol 322 pointing toward the gate 304 terminal.

The gate 304 may also be made of different materials. In some designs,the gate 304 is made from polycrystalline silicon, also referred to aspolysilicon or poly, which is a conductive form of silicon. Althoughreferred to as “poly” or “polysilicon” herein, metals, alloys, or otherelectrically conductive materials are contemplated as appropriatematerials for the gate 304 as described in the present disclosure.

In some MOSFET designs, a high-k value material may be desired in thegate insulator 320, and in such designs, other conductive materials maybe employed. For example, and not by way of limitation, a “high-k metalgate” design may employ a metal, such as copper, for the gate 304terminal Although referred to as “metal,” polycrystalline materials,alloys, or other electrically conductive materials are contemplated asappropriate materials for the gate 304 as described in the presentdisclosure.

To interconnect to the MOSFET device 300, or to interconnect to otherdevices in the die 106 (e.g., semiconductor), interconnect traces orlayers are used. These interconnect traces may be in one or more oflayers (e.g., 210-214), or may be in other layers of the die 106.

FIG. 4 illustrates a transistor in accordance with an aspect of thepresent disclosure. A fin-structured FET (FinFET 400) operates in asimilar fashion to the MOSFET device 300 described with respect to FIG.3. A fin 410 in a FinFET 400, however, is grown or otherwise coupled tothe substrate 308. The substrate 308 may be a semiconductor substrate orother like supporting layer, for example, comprised of an oxide layer, anitride layer, a metal oxide layer or a silicon layer. The fin 410includes the source 302 and the drain 306. A gate 304 is disposed on thefin 410 and on the substrate 308 through a gate insulator 320. A height,Hfin, a width, Wfin, and a length, Lfin, represent the dimensions of thefin. In a FinFET structure, the physical size of the FinFET 400 may besmaller than the MOSFET device 300 structure shown in FIG. 3. Thisreduction in physical size allows for more devices per unit area on thedie 106.

Adjacent Device Isolation with Adjusted Work Function

As integrated circuit (IC) technology advances, device geometries arereduced. The geometry and “pitch” (spacing) between devices hassubstantially reduced in advanced logic technology. For example, in aseven (7) nanometer logic technology, the fin pitch is highly scaled(e.g., 21 to 24 nanometers) and the contacted gate pitch is alsoaggressively reduced (e.g., 39 to 45 nanometers).

Fin-based devices represent a significant advance in IC technology.Fin-based devices are three-dimensional structures on the surface of asemiconductor substrate. A fin-based transistor, which may be afin-based metal-oxide-semiconductor field-effect transistor (MOSFET),may be referred to as a FinFET. A nanowire field-effect transistor (FET)also represents a significant advance in IC technology. Agate-all-around (GAA) nanowire-based device is also a three-dimensionalstructure on the surface of a semiconductor substrate. A GAAnanowire-based device includes doped portions of the nanowire thatcontact a channel region and serve as the source and drain regions ofthe device. A GAA nanowire-based device is also an example of a MOSFETdevice.

The performance of MOSFET devices can be affected by numerous factorsincluding channel length, strain and external resistance. For example,semiconductor device operation often involves isolating one device fromanother. As result, interference between adjacent devices is onesubstantial factor that may contribute to degraded performance of MOSFETdevices. In particular, interference between adjacent devices is adevice performance and scaling limiter for advanced technology nodes inwhich the geometry and spacing between devices is dramatically reduced.

In a planar structure, a fin-based structure, a GAA nanowire-basedstructure or other like three-dimensional structures, adjacent devices,such as transistors, may be physically and/or electrically isolated. Aphysical disconnect between adjacent active areas may be performed todisconnect the active areas of adjacent transistors. The disconnectionmay involve physically breaking the active areas using, for example, acutting step to disconnect the active areas of adjacent transistors orsome other physical barrier between two adjacent devices. While such anapproach may provide complete electrical isolation, the physicaldisconnection (e.g., the cutting step) is not self-aligned. Lack ofself-alignment in the physical disconnection may lead to performancevariability, while avoiding a device area penalty to account for thephysical barrier created between the two adjacent devices.

An electrical disconnect between adjacent active areas may be performedto electrically disconnect the active area of an adjacent isolationdevice. In this electrical isolation, a nearby (or adjacent) transistormay be used as an isolation device. Such an isolation device may bereferred to as a “tie-off” device in which the active area of thetie-off device is set to an off state. An off state may be differentdepending on the type of charge carrying device. For example, in ann-type device, the tie-off device may tie a gate to a low potential,whereas for a p-type device the tie-off device may tie the gate to ahigh potential.

In related art approaches, the tie-off device (e.g., the gate of atransistor) may be of the same charge carrier as the desired activedevice. In such cases, the tie-off device may be fabricated usingsimilar processing steps to those used to fabricate active devices. Thatis, the processing steps used to fabricate the gate, source and drain,as well as the gate contacts for the tie-off device, and thecharacteristics (e.g., threshold voltage (Vt), leakage current I_(off),gate length, etc.) of the tie-off device will be similar to those usedto fabricate the active device. For example, if the active device is ahigh performance device, a threshold voltage (Vt) of the active devicemay be low. As a result, the isolation device is also fabricated with alow threshold voltage. Without physical disconnection, a non-negligibleleakage current I_(off) will exist across the isolation device becauseof the low threshold voltage (e.g., the voltage low above which thedevice is activated).

Various aspects of the disclosure provide techniques for isolatingadjacent devices by altering a work function material of either theactive device or the isolation device. The process flow for altering awork function material of either an active device or an isolation devicemay include front-end-of-line (FEOL) processes, middle-of-line (MOL)processes, and back-end-of-line (BEOL) processes.

Aspects of the present disclosure include an innovative integration flowto alter a work function material disposed on the active source/drainregions of either a fin-based active device or a fin-based isolationdevice. Additional aspects of the present disclosure can alter a workfunction material disposed on the active source/drain regions ofgate-all-around (GAA) nanowire-based devices and other likethree-dimensional structure to reduce leakage current within theisolation device. Adjacent device isolation using altered work functionmaterials may enable operation within the reduced device geometries ofadvanced logic technology, such as seven (7) nanometer logic technologyand beyond. A work function alteration is self-aligned to the activedevices and may be performed using existing materials and processcapabilities with no additional steps. This aspect of the presentdisclosure also provides a reduction in the fabrication penalty forforming an isolation device within the active circuit area.

One aspect of the present disclosure alters the work function materialof either the active device or the tie-off device, such that the activedevice and the corresponding tie-off device have different work functionmaterials. For high performance active devices, which have a lowthreshold voltage, having a similar work-function material (e.g., ap-type work function metal (PWFM) or an n-type work function metal(NWFM)) in the corresponding tie-off device increases the possibility ofleakage current. By altering the work function material of the eitheractive device or the tie-off device, which may be done in the gatestack, the threshold voltage of the tie-off device is modified from alower threshold voltage to a higher threshold voltage. This may reducethe leakage current, while providing isolation between the active deviceand other active devices, such as adjacent active devices on anintegrated circuit, without relying on physical isolation.

FIG. 5 illustrates a cross-sectional view of a fin-based integratedcircuit (IC) device 500 including altered work function material withinan isolation device in accordance with an aspect of the presentdisclosure. Representatively, the fin-based IC device 500 includes ashallow trench isolation (STI) region 504 surrounding the fins 550including doped sub-fin portions 570 and active fin portions 580supported by a substrate 502 (e.g., a semiconductor substrate, a siliconon insulator (SOI) substrate, a buried oxide (BOX) layer, or the like).An SOI substrate may be fully depleted. Each of the active fin portions580 is disposed on one of the doped sub-fin portions 570 (e.g. the dopedportions of the fins 550). When the doped sub-fin portions 570 are of ann-type (e.g., an NFET), the doped sub-fin portions 570 are composed ofphosphorous doped silicon (SiP), carbon phosphorous doped silicon(SiCP), phosphorous doped silicon germanium (SiGeP), phosphorous dopedgermanium (GeP), or other like three/five (III/V) material. When thedoped sub-fin portions 570 are of a p-type (e.g., a PFET), the dopedsub-fin portions 570 are composed of boron doped silicon germanium(SiGeB), boron doped germanium (GeB), or other like doped material.

In this arrangement, the fin-based IC device 500 includes active devices(e.g., active gates 510) and isolation devices (e.g., tie-off gates540). The active gates 510 include a first portion within an n-typeregion 520 having an n-type work function material (NWFM) 524. Theactive gates 510 also include a second portion within a p-type region530 having a p-type work function material (PWFM) 534. Similarly, thetie-off gates 540 may be formed within the n-type region 520 or thep-type region 530. In this aspect of the disclosure, however, the workfunction material of the tie-off gates 540 is altered.

For example, although one of the tie-off gates 540 is in the n-typeregion 520, the work function material is of the p-type work functionmaterial (e.g., PWFM 534). Likewise, although the other of the tie-offgates 540 is in the p-type region 530, the work function material is ofthe n-type work function material (e.g., NWFM 524). In this aspect ofthe disclosure, altering the work function material of the tie-off gates540 changes the threshold of the tie-off device from a lower thresholdvoltage to a higher threshold voltage. This may reduce the leakagecurrent while providing improved electrical isolation between the activedevice and other active devices without relying on physicaldisconnection of the isolation devices.

In this arrangement, the active gates 510 include a gate spacer 512(e.g., a nitride-based low-K gate spacer) on sidewalls of the activegates 510. A conductive fill material 516 (e.g., tungsten (W) or cobalt(Co)) is disposed on the work function material (e.g., NWFM 524 or PWFM534) of the active fin portions 580. The work function materials (e.g.,NWFM 524 or PWFM 534) are deposited on a high-k dielectric layer 514 onthe gate spacer 512. The fin-based IC device 500 may be formed as shownin FIGS. 6A-6J and 7A-7I. An IC device, according to aspects of thepresent disclosure, may include gate-all-around (GAA) nanowire-basedactive devices, fin-based active devices, or other likethree-dimensional active devices. A process for forming the fin-based ICdevice 500, as shown in FIGS. 6A-7I, is described with reference toFIGS. 10A and 10B.

FIG. 10A illustrates a method 1000 for fabricating an IC deviceincluding isolation devices having an altered work function materialaccording to an aspect of the present disclosure. The process describedin FIGS. 10A and 10B enables formation of the fin-based IC device 500,as shown in FIGS. 5, 8 and 9. In block 1002, an incoming wafer (e.g., asemiconductor substrate) is shown after the wafer etch is completed toform fins 550. For example, as shown in FIG. 6A, a hardmask 554 (e.g.,silicon nitride (SiN) and an oxide layer 552 are arranged on fins 550(e.g., a base fin portion). Although illustrated with reference to afin-based device, alteration of the work function material may beapplied to other like three-dimensional semiconductor structures, suchas the GAA nanowire-based IC device shown in FIG. 8.

Referring again to FIG. 10A, in block 1004, the n-type sub-fin regionsand the p-type sub-fin regions of the IC device are doped. For example,as shown in FIG. 6B, a p-type doped oxide 532 (e.g., boron) is formed onsidewalls of the fins 550, the oxide layer 552, and the hardmask 554within both the n-type region 520 and the p-type region 530. In FIG. 6C,a hardmask 554 is deposited on the p-type doped oxide 532 within thep-type region 530. In FIG. 6D, the p-type doped oxide 532 is removedfrom the n-type region 520 to expose one of the fins 550; the p-typedoped oxide 532 remains on the fins 550 in the p-type region 530.

In FIG. 6E, an n-type doped oxide 522 (e.g., phosphorous or arsenic) isformed on sidewalls of the fins 550, the oxide layer 552, and thehardmask 554 within the n-type region 520. In addition, the n-type dopedoxide 522 is deposited on the p-type doped oxide 532 within the p-typeregion 530. The process shown in FIGS. 6B-6E may be performed using asolid state dopant or other like well dopant. This technique avoids ionimplantation into the wells of the device while reducing sub finleakage. Fin channel doping is eliminated by not performing well ionimplantation. In one aspect of the present disclosure, a well dopant isused to replace the well implants by positioning well dopants underneaththe channel. In this aspect of the present disclosure, the active deviceas well as the isolation device exhibit a low channel dopantconcentration in an active portion of the device. The dopant may begrown using an epitaxial process. Alternatively, the dopant may be asolid state dopant or other like well dopant that is positionedunderneath the channel to replace ion implantation within the wells ofthe device.

Referring again to FIG. 10A, in block 1006, a shallow trench isolation(STI) material is deposited and etched to stop on the hardmask of thedoped sub-fin regions. As shown in FIG. 6F, a shallow trench isolationmaterial is deposited to form an STI region 504. The STI region 504 isetched to stop on the hardmask 554 of the fins 550. As shown in FIG. 6G,the STI region 504, the p-type doped oxide 532 and the n-type dopedoxide 522 are etched to expose the hardmask 554. In block 1008, thehardmask and the oxide as well as the STI region are etched to expose anactive fin portions. As shown in FIG. 6H, the hardmask 554 is removedfrom the fins 550. In FIG. 6I, the STI region 504 and the oxide layer552 are etched to expose active fin portions 580 of the fins 550.

Referring again to FIG. 10A, in block 1010, the fin-based IC device 500is annealed to drive the dopant into the doped sub-fin regions to formdoped sub-fin portions of the fins. As shown in FIG. 6J, the n-typedoped oxide 522 is driven into a base portion of the fins 550 to formdoped sub-fin portions 570 of the fins 550 within the n-type region 520to form an n-type diffused dopant 526. In addition, the p-type dopedoxide 532 is driven into the doped sub-fin regions to form doped sub-finportions 570 of the fins 550 within the p-type region 530 to form ap-type diffused dopant 536. The n-type diffused dopant 526 and thep-type diffused dopant 536 are used in place of ion implantation used inplanar devices to control sub fin leakage. The n-type diffused dopant526 and the p-type diffused dopant 536 may also provide isolationbetween the n-type region 520 and the p-type region 530. As shown inFIGS. 7A-7I, gate formation is performed in which a work functionmaterial of the isolation devices is altered to raise a thresholdvoltage of the isolation devices to reduce a leakage current of theisolation devices.

Referring to again to FIG. 10A, in block 1012, a wafer is patterned toform a dummy poly gate on active fin portions of an IC device. As shownin FIG. 7A, an incoming wafer is depicted after a dummy poly gatepatterning process is completed to form a dummy poly gate (e.g., silicon(Si)). In this example, a hardmask 501 (e.g., silicon nitride (SiN)) isarranged on the active gates 510 during the patterning of the activegates 510. The active gates 510 are supported by the STI region 504,which is supported by a substrate 502. In block 1014, a gate spacer(e.g., a nitride-based low-K gate spacer) is formed on sidewalls of thedummy gate and the hardmask. For example, as shown in FIG. 7B, a gatespacer 512 is formed on the sidewalls of the active gates 510 and thehardmask 501. In addition, an oxide 572 is deposited on the active finportions 580.

FIG. 10B further illustrates the method 1000 of FIG. 10A for fabricatingan IC device including isolation devices having an altered work functionmaterial according to an aspect of the present disclosure. In block1020, an interlayer dielectric (ILD) is deposited on the IC device and achemical mechanical polish (CMP) process is performed on the ILDmaterial to stop on and expose the poly dummy gate. As shown in FIG. 7C,the CMP process is performed on an ILD 506 to expose the active gates510. In block 1022, the dummy gate is removed and the oxide layer on theactive fin portions is refreshed. As shown in FIG. 7D, the active gates510 are removed and the oxide 572 (e.g., silicon oxide (Si0₂)) on theactive fin portions 580 is refreshed to expose the active fin portions580 of the fins 550. In block 1024, a replacement gate process isperformed to replace the dummy gate with an active gate, for example, asshown in FIG. 7E.

As shown in FIG. 7E, a high-K dielectric layer 514 is deposited on theexposed portion of the active fin portions 580 of both the active gates510 and the tie-off gates 540. A first work function material (WFM)(e.g., NWFM 524) is deposited on the active fin portions 580 within boththe n-type region 520 and the p-type region 530 of both the active gates510 and the tie-off gates 540. In this arrangement, the work functionmaterial is partially removed to form a second work function material(WFM) (e.g., a PWFM 534) in alternative ones of the n-type region 520and the p-type region 530, as shown in FIGS. 7F-7I.

Referring again to FIG. 10B, in block 1026 a gap fill material isdeposited on the work function material of a gate stack and alithographic mask is formed on the gap fill material. As shown in FIG.7F, a gap fill material 508 is deposited on the n-type work functionmaterial (e.g., NWFM 524) within both the n-type region 520 and thep-type region 530. In FIG. 7G, a lithographic mask 509 is deposited onthe gap fill material 508 to define a mask of openings within the gapfill material 508 to expose the work function material (e.g., NWFM 524)on alternating ones of the n-type region 520 and the p-type region 530.In block 1028, a strip resist is performed to form a mask opening and apartial etch of the exposed work function material then occurs. As shownin FIG. 7H, a strip resist process removes the lithographic mask 509 andforms the mask openings 560 exposing the work function material (e.g.,NWFM 524) on alternating ones of the n-type region 520 and the p-typeregion 530. For example, a partial etch of a portion of the n-type workfunction material (e.g., NWFM 524) forms the p-type work functionmaterial (e.g., PWFM 534) within the p-type region 530.

Referring again to FIG. 10B, in block 1030, the gap fill material isremoved. In FIG. 7I, the gap fill material 508 is removed to expose thework function material (e.g., NWFM 524 or PWFM 534) of both the activegates 510 and the tie-off gates 540 through the mask openings 560. Inblock 1032, a conductive fill material is deposited on the exposed workfunction material through the mask opening, and a CMP process on theconductive fill material completes the IC device. As shown in FIG. 8, aconductive fill material 816 (e.g., tungsten (W) or cobalt (Co)) isdeposited on the n-type work function material (e.g., NWFM 824) and thep-type work function material (e.g., PWFM 834) to complete formation ofthe active gates 810 and the tie-off gates 840. Finally, a CMP processis performed to stop on the ILD 806.

As shown in FIG. 8, a gate-all-around (GAA) nanowire-based IC device 800includes an STI region 804 surrounding the doped regions 870 andsupported by a substrate 802. The active regions 880 are disposed on thedoped regions 870. When the doped regions 870 are of an n-type (e.g., anNFET), the doped regions 870 are composed of a phosphorous dopedmaterial. When the doped regions 870 are of a p-type (e.g., a PFET), thedoped regions 870 are composed of a boron doped material. The GAAnanowire-based IC device 800 includes active devices (e.g., active gates810) and isolation devices (e.g., the tie-off gates 840). The activegates 810 include a first portion within an n-type region 820 having ann-type work function material (NWFM) 824, and a second portion within ap-type region 830 having a p-type work function material (PWFM) 834 on ahigh-K dielectric layer 814. The tie-off gates 840 may be formed withinthe n-type region 820 or the p-type region 830.

In one aspect of the disclosure, the work function material of thetie-off gates 840 is altered. For example, although one of the tie-offgates 840 is in the n-type region 820, the work function material is ofthe p-type work function material (e.g., PWFM 834). Likewise, althoughthe other of the tie-off gates 840 is in the p-type region 830, the workfunction material is of the n-type work function material (e.g., NWFM824). In this aspect of the disclosure, altering the work functionmaterial of the tie-off gates 840 increases a threshold voltage of thetie-off gates 840. This may reduce the leakage current of the tie-offgates 840 while providing improved electrical isolation between theactive device and other active devices without relying on a physicaldisconnection of the isolation devices (e.g., the tie-off gates 840).

In this arrangement, the active gates 810 include a gate spacer 812(e.g., a nitride-based low-K gate spacer) on sidewalls of the activegates 810. A conductive fill material 816 (e.g., tungsten (W) or cobalt(Co)) is disposed on the work function material (e.g., NWFM 824 or PWFM834) of the active regions 880. The work function material is depositedon a high-k dielectric layer 814 on the gate spacer 812. The fin-basedIC device 500 may be formed as shown in FIGS. 6A-6J and 7A-7I. Thefin-based IC device 500 may include gate-all-around (GAA) nanowire-basedactive devices, fin-based active devices, or other likethree-dimensional active devices. A process for forming the fin-based ICdevice 500, as shown in FIGS. 6A-7I, is described with reference toFIGS. 10A and 10B. This process may be modified according to aspects ofthe present disclosure for a GAA nanowire-based IC device, for example,as shown in FIG. 8.

Aspects of the present disclosure include an innovative integration flowto alter a work function material disposed on the active source/drainregions of either a fin-based active device or a fin-based isolationdevice. Additional aspects of the present disclosure can alter a workfunction material disposed on the active source/drain regions ofgate-all-around (GAA) nanowire-based devices and other likethree-dimensional structure to reduce leakage current within theisolation device. Adjacent device isolation using altered work functionmaterials may enable operation within the reduced device geometries ofadvanced logic technology, such as seven (7) nanometer logic technologyand beyond. A work function alteration is self-aligned to the activedevices and may be performed using existing materials and processcapabilities with no additional steps. This aspect of the presentdisclosure also provides a reduction in the fabrication penalty forforming an isolation device within the active circuit area.

One aspect of the present disclosure alters the work function materialof either the active device or the tie-off device, such that the activedevice and the corresponding tie-off device have different work functionmaterials. For high performance active devices, which have a lowthreshold voltage, having a similar work-function material (e.g., ap-type work function metal (PWFM) or an n-type work function metal(NWFM)) in the corresponding tie-off device increases the possibility ofleakage current. By altering the work function material of the eitheractive device or the tie-off device, which may be done in the gatestack, the threshold of the tie-off device is changed from a lowerthreshold voltage to a higher threshold voltage. This may reduce theleakage current and also may provide isolation between the active deviceand other active devices, such as adjacent active devices on anintegrated circuit.

According to an aspect of the present disclosure, a fin-based structureis described. In one configuration, the fin-based structure includesmeans for isolating between fins of the fin-based structure. Theisolating means may be an isolation device (e.g., tie-off gates540/840). In another aspect, the aforementioned means may be any moduleor any apparatus or material configured to perform the functions recitedby the aforementioned means.

FIG. 11 is a block diagram showing an exemplary wireless communicationsystem 1100 in which an aspect of the disclosure may be advantageouslyemployed. For purposes of illustration, FIG. 11 shows three remote units1120, 1130, and 1150 and two base stations 1140. It will be recognizedthat wireless communication systems may have many more remote units andbase stations. Remote units 1120, 1130, and 1150 include IC devices1125A, 1125C, and 1125B that include the disclosed isolation deviceswith altered work functions. It will be recognized that other devicesmay also include the disclosed isolation devices, such as the basestations, switching devices, and network equipment. FIG. 11 showsforward link signals 1180 from the base station 1140 to the remote units1120, 1130, and 1150 and reverse link signals 1190 from the remote units1120, 1130, and 1150 to base stations 1140.

In FIG. 11, remote unit 1120 is shown as a mobile telephone, remote unit1130 is shown as a portable computer, and remote unit 1150 is shown as afixed location remote unit in a wireless local loop system. For example,the remote units may be a mobile phone, a hand-held personalcommunication systems (PCS) unit, a portable data unit such as apersonal data assistant, a GPS enabled devices, a navigation device, aset top box, a music players, a video player, an entertainment unit, afixed location data unit such as meter reading equipment, or otherdevices that store or retrieve data or computer instructions, orcombinations thereof. Although FIG. 11 illustrates remote unitsaccording to the aspects of the disclosure, the disclosure is notlimited to these exemplary illustrated units. Aspects of the disclosuremay be suitably employed in many devices, which include the disclosedisolation devices.

FIG. 12 is a block diagram illustrating a design workstation used forcircuit, layout, and logic design of an IC structure, such as theisolation devices disclosed above. A design workstation 1200 includes ahard disk 1201 containing operating system software, support files, anddesign software such as Cadence or OrCAD. The design workstation 1200also includes a display 1202 to facilitate design of a circuit 1210 oran IC device 1212 including an isolation device. A storage medium 1204is provided for tangibly storing the design of the circuit 1210 or theIC device 1212. The design of the circuit 1210 or the IC device 1212 maybe stored on the storage medium 1204 in a file format such as GDSII orGERBER. The storage medium 1204 may be a CD-ROM, DVD, hard disk, flashmemory, or other appropriate device. Furthermore, the design workstation1200 includes a drive apparatus 1203 for accepting input from or writingoutput to the storage medium 1204.

Data recorded on the storage medium 1204 may specify logic circuitconfigurations, pattern data for photolithography masks, or mask patterndata for serial write tools such as electron beam lithography. The datamay further include logic verification data such as timing diagrams ornet circuits associated with logic simulations. Providing data on thestorage medium 1204 facilitates the design of the circuit 1210 or thefin-based structure 1212 by decreasing the number of processes fordesigning semiconductor wafers.

For a firmware and/or software implementation, the methodologies may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. A machine-readable mediumtangibly embodying instructions may be used in implementing themethodologies described herein. For example, software codes may bestored in a memory and executed by a processor unit. Memory may beimplemented within the processor unit or external to the processor unit.As used herein, the term “memory” refers to types of long term, shortterm, volatile, nonvolatile, or other memory and is not to be limited toa particular type of memory or number of memories, or type of media uponwhich memory is stored.

If implemented in firmware and/or software, the functions may be storedas one or more instructions or code on a computer-readable medium.Examples include computer-readable media encoded with a data structureand computer-readable media encoded with a computer program.Computer-readable media includes physical computer storage media. Astorage medium may be an available medium that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can include RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, orother medium that can be used to store desired program code in the formof instructions or data structures and that can be accessed by acomputer; disk and disc, as used herein, includes compact disc (CD),laser disc, optical disc, digital versatile disc (DVD), floppy disk andBlu-ray disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers. Combinations of the aboveshould also be included within the scope of computer-readable media.

In addition to storage on computer readable medium, instructions and/ordata may be provided as signals on transmission media included in acommunication apparatus. For example, a communication apparatus mayinclude a transceiver having signals indicative of instructions anddata. The instructions and data are configured to cause one or moreprocessors to implement the functions outlined in the claims.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the technologyof the disclosure as defined by the appended claims. For example,relational terms, such as “above” and “below” are used with respect to asubstrate or electronic device. Of course, if the substrate orelectronic device is inverted, above becomes below, and vice versa.Additionally, if oriented sideways, above and below may refer to sidesof a substrate or electronic device. Moreover, the scope of the presentapplication is not intended to be limited to the particularconfigurations of the process, machine, manufacture, composition ofmatter, means, methods and steps described in the specification. As oneof ordinary skill in the art will readily appreciate from thedisclosure, processes, machines, manufacture, compositions of matter,means, methods, or steps, presently existing or later to be developedthat perform substantially the same function or achieve substantiallythe same result as the corresponding configurations described herein maybe utilized according to the present disclosure. Accordingly, theappended claims are intended to include within their scope suchprocesses, machines, manufacture, compositions of matter, means,methods, or steps.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The steps of a method or algorithm described in connection with thedisclosure may be embodied directly in hardware, in a software moduleexecuted by a processor, or in a combination of the two. A softwaremodule may reside in RAM, flash memory, ROM, EPROM, EEPROM, registers,hard disk, a removable disk, a CD-ROM, or any other form of storagemedium known in the art. An exemplary storage medium is coupled to theprocessor such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. The processor and the storagemedium may reside in an ASIC. The ASIC may reside in a user terminal. Inthe alternative, the processor and the storage medium may reside asdiscrete components in a user terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can include RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store specified program code means in the form of instructions ordata structures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), and Blu-ray disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

1. An integrated circuit (IC) device, comprising: a first activetransistor of a first-type in a first-type region, having a first-typework function material and a channel dopant concentration in an activeportion of the first active transistor; and a first isolation transistorof the first-type in the first-type region having a second-type workfunction material and the channel dopant concentration in an activeportion of the first isolation transistor, the first isolationtransistor being adjacent to the first active transistor.
 2. The ICdevice of claim 1, further comprising a second active transistor of asecond-type in a second-type region, having the second-type workfunction material; and a second isolation transistor of the second-typein the second-type region having the first-type work function material,the second active transistor being adjacent to the second isolationtransistor.
 3. The IC device of claim 1, further comprising a thirdactive transistor adjacent to the first isolation transistor in thefirst-type region, the third active transistor being electricallyisolated from the first active transistor by the first isolationtransistor, having a higher threshold voltage than the first activetransistor and the third active transistor.
 4. The IC device of claim 1,in which a gate of the first isolation transistor is biased to place thefirst isolation transistor in an OFF state.
 5. The IC device of claim 1,in which the first-type is an n-type and the first-type region is ann-type region and the second-type work function material is a p-typework function material, and in which the first isolation transistor isdisposed in the n-type region with the p-type work function material toprovide a higher threshold voltage than the first active transistor. 6.The IC device of claim 1, in which the first active transistor and thefirst isolation transistor comprise a fin field-effect transistor(FinFET) and the active portion comprises a fin of the FinFET.
 7. The ICdevice of claim 6, in which a first active FinFET and a first isolationFinFET comprise an active fin portion on a doped fin portion, the dopedfin portion doped with a solid state dopant.
 8. The IC device of claim1, in which the first active transistor and the first isolationtransistor comprise a gate-all-around nanowire field-effect transistor(FET).
 9. The IC device of claim 1 integrated into a mobile phone, a settop box, a music player, a video player, an entertainment unit, anavigation device, a computer, a hand-held personal communicationsystems (PCS) unit, a portable data unit, and/or a fixed location dataunit.
 10. A method for altering a work function material of an isolationtransistor within an integrated circuit (IC) device, the methodcomprising: exposing a first-type work function material of theisolation transistor disposed adjacent to a first-type active transistorin a first-type region; etching the first-type work function material ofthe isolation transistor to form a second-type work function materialfor the isolation transistor within the first-type region; anddepositing a conductive fill material on the second-type work functionmaterial of the isolation transistor.
 11. The method of claim 10,further comprising biasing a gate of the isolation transistor is toplace the isolation transistor in an OFF state.
 12. The method of claim10, further comprising doping a source/drain portion of the first-typeactive transistor and the isolation transistor using a solid statedopant.
 13. The method of claim 10, in which exposing comprises:depositing a mask to define openings to the isolation transistor withinalternating n-type regions and p-type regions; and performing a stripresist process to expose the isolation transistor within the alternatingn-type regions and p-type regions.
 14. The method of claim 10, in whichthe IC device is integrated into a mobile phone, a set top box, a musicplayer, a video player, an entertainment unit, a navigation device, acomputer, a hand-held personal communication systems (PCS) unit, aportable data unit, and/or a fixed location data unit.
 15. An integratedcircuit (IC) device, comprising: a first active transistor of afirst-type in a first-type region, having a first-type work functionmaterial and a channel dopant concentration in an active portion of thefirst active transistor, the active portion comprising an active finportion on a doped fin portion; and a first means for isolating thefirst active transistor, the first isolating means being adjacent to thefirst active transistor.
 16. The IC device of claim 15, furthercomprising a second active transistor of a second-type in a second-typeregion, having a second-type work function material; and a second meansfor isolating the second active transistor, the second active transistorbeing adjacent to the second isolating means.
 17. The IC device of claim15, further comprising a third active transistor adjacent to the firstisolating means in the first-type region, the third active transistorbeing electrically isolated from the first active transistor by thefirst isolating means, having a higher threshold voltage than the firstactive transistor and the third active transistor.
 18. The IC device ofclaim 15, in which the first isolating means comprises a first isolationtransistor of the first-type in the first-type region having asecond-type work function material and the channel dopant concentrationin an active portion of the first isolation transistor, and a gate ofthe first isolation transistor is biased to place the first isolationtransistor in an OFF state.
 19. The IC device of claim 15, in which thefirst-type is an n-type and the first-type region is an n-type regionand a second-type work function material is a p-type work functionmaterial, and in which the first isolating means comprises a firstisolation transistor disposed in the n-type region with the p-type workfunction material to provide a higher threshold voltage than the firstactive transistor.
 20. The IC device of claim 19, in which the firstactive transistor and the first isolation transistor comprise a finfield-effect transistor (FinFET) and the active portion comprises a finof the FinFET.
 21. The IC device of claim 20, in which a first activeFinFET and a first isolation FinFET comprise the active fin portion onthe doped fin portion, the doped fin portion doped with a solid statedopant.
 22. The IC device of claim 15, in which the first isolatingmeans comprises a first isolation transistor and in which the firstactive transistor and the first isolation transistor comprise agate-all-around nanowire field-effect transistor (FET).
 23. The ICdevice of claim 15 integrated into a mobile phone, a set top box, amusic player, a video player, an entertainment unit, a navigationdevice, a computer, a hand-held personal communication systems (PCS)unit, a portable data unit, and/or a fixed location data unit.
 24. Amethod for altering a work function material of an isolation transistorwithin an integrated circuit (IC) device, the method comprising: thestep for exposing a first-type work function material of the isolationtransistor disposed adjacent to a first-type active transistor in afirst-type region; the step for etching the first-type work functionmaterial of the isolation transistor to form a second-type work functionmaterial for the isolation transistor within the first-type region; andthe step for depositing a conductive fill material on the second-typework function material of the isolation transistor.
 25. The method ofclaim 24, further comprising the step for biasing a gate of theisolation transistor is to place the isolation transistor in an OFFstate.
 26. The method of claim 24, further comprising the step fordoping a source/drain portion of the first-type active transistor andthe isolation transistor using a solid state dopant.
 27. The method ofclaim 24, in which the step for exposing comprises: the step fordepositing a mask to define openings to the isolation transistor withinalternating n-type regions and p-type regions; and the step forperforming a strip resist process to expose the isolation transistorwithin the alternating n-type regions and p-type regions.
 28. The methodof claim 24, in which the IC device is integrated into a mobile phone, aset top box, a music player, a video player, an entertainment unit, anavigation device, a computer, a hand-held personal communicationsystems (PCS) unit, a portable data unit, and/or a fixed location dataunit.